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Topic: VOX AC and Hiwatt amps (Read 21204 times)

Been browsing my downloaded schematics for my first all-tube amp build. Looking at a 50 Watter. I'm thinking of just going hybrid. Like tube preamp, solid state tone control and phase splitter, then tube power amps. I'll just adjust the voltage and impedance requirements closely. That way I can limit the tube count to just three.

It seems that the VOX AC amps and the Hiwatts are much simpler than Marshalls to build. Tube count is roughly the same for equal wattage, but the number of passive components are much less for those two amps.

Has anyone had any experience with those ? They're awfully rare in the RP. Will it approximate the "brown sound" that Marshall fans like me adore ?

Been browsing my downloaded schematics for my first all-tube amp build. Looking at a 50 Watter. I'm thinking of just going hybrid. Like tube preamp, solid state tone control and phase splitter, then tube power amps. I'll just adjust the voltage and impedance requirements closely. That way I can limit the tube count to just three.

It seems that the VOX AC amps and the Hiwatts are much simpler than Marshalls to build. Tube count is roughly the same for equal wattage, but the number of passive components are much less for those two amps.

Has anyone had any experience with those ? They're awfully rare in the RP. Will it approximate the "brown sound" that Marshall fans like me adore ?

BAMF

I'm not an expert but it seems building a Vox or Hiwatt are complicated for a first build? Have you tried building an AX84? I think they have different flavors naman -- or give one your own Vox/Hiwatt flavor.

Al : Gave it lots of thought. Figgers that natural marble will entail too much expense and time as I might have to travel to Romblon just for it.

I had a better idea. Cultured marble made from Resin and calcium carbonate. It won't need to be carved, it can be molded . Mixture can even be modified so that the body will be cultured granite so I can have a "hard rock guitar" .

If you could help by donating a strat body that's lying around, I'd be much obliged. I need something to mold around.

Delta: Yup I've looked at the AX84 site a couple of times. Very interesting, but the power output on the original circuits are...well...kinda low. The expense between those and 50 Watt things won't be too great.

Will the parts be 100% locally sourced including the power and output transformers? I've been wanting to build the Ax84 P1 for ages but have given up on the idea because I don't think there is a local substitute for the Hammond output and power transformers listed on the bill of materials. I'm not planning to order online either because it's darn expensive.

I actually don't know anything about electronics but I think the AX84 schematics are simple enough for mere mortals to understand. Documentation is abundant as well. It would definitely be a great way to acquire a new skill set. That is if I don't get zapped by 300 volts!

Yeah, the goal is to have all parts sourced locally (although some, like the tubes are imported but still bought locally).

The power supply transformer is the easy part. Deeco (Ill check if they still have this service ) used to have a service where they'd wind transformers for you. I've had a couple made already, but they were power transformers with specific voltages. WHen I was starting out in electronics...gosh back in 82, there was a company called "Lion" whose specialty it was to wind all kinds of transformers, power, input matching, output matching, balun, hi-voltage step-ups etc. I'll just trace where they went. Which reminds me...we were taught in school to wind our own transformers...hmmm...I just have to find the formulas. But mechanically it's simple enough...determine the wire gauge required to carry the current requiremen, how long it needs to be and wind it on a plastic bobbin (can be bought at deeco) then cover that layer with masking tape, wind your primary winding over it. THen insert the "E" cores alternately from left and right until the bobbin is filled with it. fill the gaps outside the bobbin with the "I" cores until there are no more gaps. Dip in varnish and screw the thing down. Hey thanks for reminding me .

Aww looky here zook. Right under my very nose. Alexan has a custom transformer winding service. And output transformers (both Hammond and local AMX) are available from kinetic audio in Cainta. Must be my lucky night. Now the next question of how much .

without any disrespect, but have you really heard what a good AC30 sounds like in person? If so, how many? If not, how do you know that you are voicing the correct sound?

this is my point... wala tayo sa position to make amps that sound good because we are not exposed... period

Heya oas. Actually, that's exactly the question of this thread. I have not heard not even one AC, except the records of the Beatles and have not heard a Hiwatt, except from the records of The Who. That's why I'm asking if anyone has heard one and what are their comments.

My target sound is Marshall, of which I have been plugged into tens of them,and have one, albeit solid state. I'm just asking if it approximates Marshall. Yep, in this regard I truly admit that I'm clueless to the AC30's and Hiwatts.

As for not in the position to make amps that sound good...that's a very limiting belief. I'll be the judge of that, when it's done, and not prior to actually doing it. Even a Jim Marshall started from zero when he cloned the Fender tweed. As for me, I can make my mistakes, learn, and adjust again. After all, it will be my personal unit, I can do with it whatever I damn please. . I do have 23 years of electronics building experience under my belt and have built some nasty solid-state's in my heyday. This is admittedly my first tube build.

Oh yeah. My brother 10 years my senior, who's a fellow ECE and the pro audio engineer between the two of us still has questions about why a speaker sounds good and why some don't. Together with the mythical Marshall output transformer, that's the "myth" part which still needs to be figgered out. And these darn things are not made equal. A celestion will not sound like the next one, even if it's made exactly the same. The truth is out there somewhere .

But I'll be starting with Crown or Dai-ichi instrument speakers for the moment and start from there. Thinking of a closed-back cabinet too to add bass punch. That's where I'll need my bro's help .

Will you be willing to hand build a state-of-the-art B-A-M-F! power transformer for a poor soul like me? Hehehe, just kidding! I will check out Deeco and Alexan for their custom winding service and many thanks for the tip, you've been very helpful. Oh, pardon my laziness but do you have the address of Kinetic Audio in Cainta? Mr. Google did not yield any interesting results.

I'm sure tube amp DIYers will frown upon this. Some AX84 enthusiasts swear by the sound of Hammonds. Others will bet their life on some so-and-so piece of equipment. Swat the Duck! I'm not willing to shell out cash for a piece of heavy iron. We are Pinoy and we ARE damned resourceful. We will use materials that are readily available. I think the satisfaction here comes from building something out of nothing. By relying on ones' skill, creativity and DISKARTE we are able to come up with something we can call our own. Ultimately, it is our own ears that will judge whether the end product sounds good. If the end product does not sound like a true VOX or a Hi-Watt or a Marshall, it doesn't really matter. What's important is that we built it ourselves.

zook: Scroll up a little, I pasted Kinetic Audio's contact numbers in a previous post. They carry Hammond Transformers .

I agree with y' both. Of course the objective is important, but if we fall short, it was really the journey and not the destination. And if I don't hit a marshall sound, maybe it will be a BAMF sound if it doesnt approach anything else. Not a total waste.

At any rate, I was reading up literature til 7 am this mornin, wasnt able to sleep. Lots of factors that go into the sound and I believe some of these are not just myths. Like the metal used for the output transformer core and the way the transformer is wound. I've read somewhere that the best output transformers are "bifiliar" or "trifiliar" wound, meaning the primary and secondary coil wires are wound around together and not in layers. It's a myth that actually makes sense. Then I was able to find a "Marshall Tone Stack" which is to say that it's the unique way that Marshall configures its tone controls. Yes, it does look quite assymetrical and unusual, and right now I'm beginning to understand the high passive parts count of marshall. The El Tubero preamp is now complete and is relatively silent (as overdrives go anyway). It appears it was noisy because I forgot to put in a shunt resistor on the output. I'm already happy with its sound, it's got this "glassy", brittle sound and when you strum full chords, it goes "quack". Is that a good thing? Sounds good to me...although a little more perfection is in order. Kumbaga sa golf, its about 3 putts away from Marshall sound pa. I'll implement the Marshall tone stack on it and if it gives me a 1 putt away or hole in one, I could stop there, short of building a tube amp (bakit pa kumbaga).

Dantuts : Output transformers are actually impedance matching transformers. They convert the impedance from the side of the tubes to the 8 or 16 ohms required by the speakers. Kinetic audio has Hammonds btw, or so they say in their website. Scroll up and call them up By the way, their retail arm is Phasetron audio in park square 1 glorietta. They also have custom-wound transformer service. Malamang pang hi-fi pa and local so I hope to get a high cost to quality ratio if I go that way .

this is my point... wala tayo sa position to make amps that sound good because we are not exposed... period

I believe it's a very colonial view to think that something that sounds "good" should sound like some other thing which is touted to be so.. An object's real merit can only be seen if it's judged against itself, not against things that were obviously designed to do other things.

Being exposed to different tones will definitely create a good starting point but the lack of it should not be a factor that inevitably destroys the potential to create something that's good. After all, Leo Fender never heard a "real" guitar amp prior to his designs. Jim did hear Fender amps but that was about it. Radio and stereo systems were the closest thing they had to instrument amplification.

I support BAMF in his endeavor and am very excited to hear what he comes up with.

BAMF - wow! lots of great info here. i, too, am excited to hear about the results of your project (yours too, zook, if you decide to take the plunge). pag makabuo kayo ng prototype from local materials, i will follow suit regardless of the tone. as an initial foray into tube amp building, what's important is acquiring the know-how in building it. pag marunong na ako mag-build, then i'll go into tweaking them to sound good to me!

btw, tama ka about the Marshall transformers. i think "interleaved" is the term they call that type of winding. i've read the theory behind its sound and it did make a lot of sense. as for the tone control, i think you are referring to the Baxandall type of eq control, unlike the very common Fender style. i had a THD Univalve amp dati that had that type of tone control and it basically leaves the mid-range alone when you cut the bass and trebles, giving the impression of boosted mids. as you already know, Marshalls are renowned for those delicious mids.

When I talk to the Boutique amp manufacturers, they are already so far away on the learning curve. They never claim they are ECE graduates or anything but tell you what works and what doesn't rather bluntly. Its when you actually try a product that you start to understand what they are after. Beyond schematics and parts, they are after magic and I have seen and heard what they can produce.

For example, Todd Sharp never claims ever that this specific model of a Vox AC30 is the best sounding but what he does claim is that the sound of the best vox that he has heard is in his head which none of us may even experience in our lifetime because of the limited number of good vintage sounding voxes will ever hear -- not all vintage voxes sound great. With regards to marshall, even the US guys will tell you only selected Marshall heads of even the vintage variety sound great and they are careful which specific model to blueprint and copy. Its is true that something can be judged as subjective but the key is to produce something that a great majority will judge as good sounding not only by yourself. What you are thinking about, I thought myself a long time ago until I realized that I don't have the ears for it and more importantly we are not exposed to the great guitarists of our times in the Philippines. If you ever talk to Van Halen, Brad Gilis, Larry Carlton, Eric Clapton, Steve Lukather, George Lynch, John Petrucci, Scott Henderson or SRV -- you get the point, then lets start making amps. These guys are musicians who are known to work with Amp makers and we lose out on that.

I have never liked Fender Amps. But I am willing to try out Victoria. The best clean channel I have heard is Rivera's clean channel on this TBR models and the bright low gain of a Vox AC30. I am not trying to be colonial but rather indicative of who is what I consider leading edge in terms of guitar amp development. Beyond features, guitar amp manufacturers are now looking at magic -- the ability to inspire to play as their selling point. Do not mistake my being colonial -- I am just trying to be frank. I still think Filipinas are one of the most beautiful women in the world and so are the girls of Destiny's Child. An amp's real merit I believe is its ability to inspire if not all at least a great majority of guitarists who plug into it.

for Vox AC30, they are cathode biased ("class a" though not really) EL84 amps and they have SEVERAL, CHEAPER (not necessarily inferior) clones, like Crate V3112 and Laney VC30, might want to take at look at them too. Meron din mas mahal and much complex such as the Mesa Lonestar Special hehe.

Okay guys, baka sabihin nyo pinapasakay ko lang kayo So here's a soundclip of the El Tubero preamp. Good lessons learned here en route to building my first tubo amp. Including NEVER PUT THE PLATE VOLTAGE ON THE END OF A TERMINAL STRIP WHICH HAS THE MOUNTING SCREW ON IT (this buzzed me with 300+ volts a couple of times before I figgered out why). Hehehe. Meron palang mga Sovtek na tubo sa Audiophile ! Nyehehehe. At mura lang yung iba, yung 6550 na allparts, parang 1 k lang for a matched pair ! Power tubes yun ! China nga lang, pero the goal is an affordable, if not cheap, tube amp. Meron ding mahal, 5 thou ang isang piraso (nobayan!!!)

Anyways, eto sya. I flatted all EQ, somehow I can't get it to quack (must be in the mids or highs section which got cut out). Here are the parameters that may color the sound :

1. Guitar- RJ PRS copy with el cheapo Lazer Humbucker on bridge pickup. 2. All EQ is flat3. Miked 6 inches away4. Main amp is a JR50. Actually, not really coz I already pulled out the power amp section of this beast and replaced it with a 100 Watt solid state power amp module. Anyway, it should be "solid-state linear". 5. Mic is a Hyundai from a videoke machine6. No reverb (the JR50 doesnt have it anyway). 7. Gain setting is somewhere between 1/4 and 1/3. Higher settings are unusable because of a "whistling" sound that ensues when you strum.8. Input mixer/mic preamp is a 4-input el cheapo china mixer

Okay na din...sounds good...albeit, it still needs some modifications to the final 1/2 of the 12AX7. Needs a lower bias resistor to it can handle the high signal feed from the first half of the tube without choking out. Kumbaga, we love tubes coz they "breathe" kaso eto parang me hika, kinakapos ng hininga at high gain settings. . Hindi ako nakabili ng capacitors for the Marshall tone stack, masyado maliliit at walang stock ang malapit na electronics store. I'll try Raon a little later today and finish this monster.

I actually rely on both. I cannot entirely depend on my ears because I have to assess whether what I am hearing can also be heard by others. Each of us has a different way of hearing things. This is my bias: I am in favor of boutique amps and some of the older stuff. This means I talk to and deal with high end US amp retailers, Ultrasound on the East Coast and Amp Shop in the West Coast. They have and I mean have the best sounding amps in the world under one roof. Specially Ultrasound.

I rely on them to give an honest assessment of an amp because: they have everything or close to tried everything -- they have 5 dumbles I think and several Komets, Bruno, Diezels, VHTs, Bad Cats, CAAs, Matchless, Alessandro, Victorias, Marshalls and even some Peaveys, etc...., they have soundproof rehearsal rooms, they dont have degrees in engineering so to they tend to be more honest because no matter how expensive an amp -- they will tell you if it sounds lousy, they always ask for your type of music and are sensitive to what particular sound you want, most importantly they have a real vintage Gibson 59 sunburst to test and calibrate their amps. I thought initially it would be cool to have a KOMET because I heard they were sensitive amps and I felt I would be ASTIG sa Philippines but Ultrasound discouraged me and insisted that I get the Diezel Herbert because they felt it was a better amp for the music that I wanted. They were also concerned about the operating level and felt the Diezel sounded good at any volume versus the KOMET which only sounded good when cranked which they felt was really loud and not for the Philippine situation. Given that set up, how can we with our limitations pretend to know how the real good amps sound? We talk about the elusive sound of Voxes and Marshalls that we want to copy but they have 5 Dumbles to plug in anytime of day and vintage Voxes and Marshalls are just plain vanilla and they are selective about those too.

When I talk to the Boutique amp manufacturers, they are already so far away on the learning curve. They never claim they are ECE graduates or anything but tell you what works and what doesn't rather bluntly. Its when you actually try a product that you start to understand what they are after. Beyond schematics and parts, they are after magic and I have seen and heard what they can produce.

For example, Todd Sharp never claims ever that this specific model of a Vox AC30 is the best sounding but what he does claim is that the sound of the best vox that he has heard is in his head which none of us may even experience in our lifetime because of the limited number of good vintage sounding voxes will ever hear -- not all vintage voxes sound great. With regards to marshall, even the US guys will tell you only selected Marshall heads of even the vintage variety sound great and they are careful which specific model to blueprint and copy. Its is true that something can be judged as subjective but the key is to produce something that a great majority will judge as good sounding not only by yourself. What you are thinking about, I thought myself a long time ago until I realized that I don't have the ears for it and more importantly we are not exposed to the great guitarists of our times in the Philippines. If you ever talk to Van Halen, Brad Gilis, Larry Carlton, Eric Clapton, Steve Lukather, George Lynch, John Petrucci, Scott Henderson or SRV -- you get the point, then lets start making amps. These guys are musicians who are known to work with Amp makers and we lose out on that.

Forgive me if I might sound a little abrasive...but...so what's the point ? I already know that Marshalls are not made equal, Marshall heaven (to me) is a JCM 800 (and a very specific unit which I don't know where it is right now) with TSL's in close second, and Marshall hell to me are the Valvestates (specially MIJ ones) and my own G15R. But they're still Marshalls and I will love them over any fender or Peavey. Again that's just me.

From your line of reasoning again, my amp might not be the best amp but it might be the best sounding amp TO ME (or not). It's gravy if other musicians within my reach will appreciate it too. If not, then I won't commercialize and just enjoy my creations by myself. So what's your point ?

As for Lukather, Van Halen, Clapton, of course I respect them and they are my guitar heroes. But I am not seeking their validation and if they tell me that I can't build an amp, or at least even try, then I'll tell them to kiss my brown, hairy, all-Pinoy arse.

This is quite ironic coming from a guy who claims to objectively hear the difference between an ordinary cheapo resistor and a Riken Ohm. You can't tell a good amp from a bad one ? Please don't inflict upon me nor anyone else your own self-created limitations.

Okay, I'll just summarize what I believe is your point, and in no uncertain terms. I think I can do it, or learn it, or approach it, and am going...while you told yourself that you don't have the ears for it and stopped. Like I said, it's the journey, not just the destination.